The act of "half cumming" in which a man can feel ejaculation coming on, and then, at the first twitch of his scrotum, can control and then stop the orgasm, thus creating stamina he didn't know he had!

Jack was in full control until his girlfriend started screaming for him to come which caused "pre-ejaculation", but, after much concentration about tennis, he was able to stop his scrotum from twitching, and instead of cumming, rode for another hour and 11 minutes!